It is well established that visual behavior is influenced by both bottom-up visual factors and top-down cognitive factors. Consequently, a number of investigations have sought to determine how visual behavior is influenced by different task sets, which refers to the goal of an observer when they process a scene. For example, task set has been shown to strongly influence which objects are fixated, how memory influences refixations and probe detection, the timing and location of fixations, and the timing and duration of global relative to local modes of attention to name just a few. Though task set clearly influences visual behavior, the majority of task set studies require participants to perform a single task on a singl image or continuously perform a single task on a variety of images. These investigations ignore the fact that, in the real world, the task set of an individual can change frequently and rapidly a a function of observer intent, during which the visual input could change slightly, change drastically, or remain constant. To understand the influence of task set on visual behavior, therefore, it is important to investigate the influence of task switching. The study of task switching has a rich history in psychology, with numerous demonstrations that the requirement to switch tasks leads to a variety of behavioral costs and benefits. Surprisingly, however, there have been few investigations of how task switching impacts visual behavior, with existing studies being primarily concerned with the executive control required to perform prosaccades and antisaccades. To fully understand the manner in which visual behavior is impacted by previous experiences, it is critical to determine whether subsequent processing of a visual input is fundamentally altered when a) the input remains the same but the observer's goal changes and b) when the visual input changes but the task goals remain consistent. The present proposal will address this gap in knowledge by conducting sixteen experiments examining the influence of task-switching on visual behavior. The experiments are designed to assess the primary costs and benefits associated with task-switching (E1) and how these are moderated by scene repetition (E2, E6-8), alternation predictability (E3, E5, E6, E8), repetition probability (E, E5, E7, E8), and whether the instructions emphasize bottom-up (E1-8) or top-down (E9-16) factors. The proposed research has both theoretical and practical implications as it relates to the manner in which visual behavior is influenced by task-switching. Given that the present study concerns the basic functioning of the normal, adult visual system, it contributes to the scientific understanding of visual-cognitive mechanisms in the brain. In addition, the proposed research concerns costs and benefits relating to visual mechanisms that support efficient gaze control and oculomotor behavior which has significant implications for performance across a variety of fields in which visual task- switching is an important component of everyday performance.